This invention relates generally to the field of hearing testing devices, and more particularly to a portable hearing threshold tester which generates a number of test tones.
Education and training have always been important parts of hearing loss prevention programs. This includes training regarding noise exposure and hearing protection. Unfortunately, it is difficult to convince every person or worker exposed to noise that hearing protection is in their own long range interest. Even when hearing protection is worn, it is a difficult task for hearing conservation professionals to estimate hearing protector performance. There are standardized procedures for rating hearing protectors, but these ratings are for groups of people, not for individuals. An individual may find that a particular hearing protector provides much less or perhaps more protection for them than the average person. In addition, a person may be more sensitive to noise exposure than the average population. For instance, one individual may develop no temporary hearing loss when exposed to 85 dB of noise, where another person may develop 30 dB of temporary hearing loss.
There are procedures for measuring the effectiveness of head set or ear muff type protectors by making measurements under the ear muff. For example, Sound Technologies has introduced a system called the Verifier, for making measurements under an insert type of plug. These testing systems work well to show that an individual can or cannot obtain sufficient protection from a particular type of hearing protector, but they cannot serve as an easy check to see if the protector is fitted properly every time it is actually used. Currently, it is difficult to quickly and efficiently test the effectiveness of hearing protectors.
One standard approach used to check the effectiveness of hearing protectors is to test for any elevation of a person""s hearing threshold during or after noise exposure. An audiogram is normally administered by a trained professional use specialized audiometric equipment to test a person""s hearing threshold. These current hearing testing devices are large and cumbersome. As a result, they require space for the testing equipment and a quiet area to perform the hearing test. Current hearing testing devices also require the constant attention of a trained professional to test the hearing of the subject. Because a hearing professional is needed to run the equipment, it is unlikely that a hearing test will normally take place on-site where the noise exposure takes place.
Employers, managers, and owners of areas that have a high level of noise exposure are also reluctant to administer frequent hearing tests because of the inherent cost and potential liability. Another problem is that the hearing testing may interfere with an employee""s work schedule, if it is performed on a regular basis. Further, employees may consider hearing testing a nuisance and employers are opposed to any decline in productivity it creates. All the factors described above make it difficult to perform on-site hearing testing where high levels of sound exposure exist.
When hearing testing takes place, a person is normally tested to determine their current hearing threshold. A person""s hearing threshold is the softest or weakest sound that can be heard. Typically, changes in hearing thresholds come from noise exposure. They may also occur from sickness, head injuries, or exposure to toxic substances such as lead or carbon monoxide. These changes can be either temporary or permanent. With noise exposure, the changes are more likely to be temporary, lasting from a few minutes to many hours or days. This type of temporary hearing loss is known as temporary threshold shift (TTS). In other words, certain tones, i.e., frequencies, at specific sound levels or decibels may temporarily be inaudible to a person who is experiencing TTS. It is important to know if a certain type of noise a person is exposed to is producing TTS. This way the exposure can either be avoided or reduced by using hearing protectors. In the case where hearing protectors are being worn, TTS indicates that the hearing protection is not performing adequately. Being able to quickly and inexpensively test for TTS allows an individual to improve their hearing protection and avoid overexposure to harmful sounds. The current state of the art does not provide any quick, cost-effective or simple method of testing TTS and hearing loss without having a trained professional perform a complete audiogram.
Accordingly, it would be an improvement over the state of the art to provide a new method and apparatus for testing hearing which can be self-administered and does not require a trained professional to administer the test. Another improvement would be to provide a hearing tester which is portable and inexpensive. In addition, it would be advantageous to provide a device which allows an individual to quickly and easily evaluate the performance of a hearing protection device they are using. A further improvement would be to build a hearing tester into a noise measurement device worn by a person such as a noise dosimeter.
It is an object of the present invention to provide a hearing tester for testing a person""s hearing without the attention of a skilled professional.
It is a further object of the present invention to provide a hearing tester which is portable.
It is another object of the present invention to provide a hearing tester that is inexpensive and simple to use.
It is another object of the present invention to provide a hearing tester that can be used immediately after noise exposure.
It is yet another object of the invention to provide a hearing tester to enable a person to evaluate the performance of the hearing protection device they are using.
The presently preferred embodiment of the present invention is a portable hearing threshold tester which has a discrete tone generator, which generates a discrete tone with two or more discrete decibel levels near the hearing threshold for each discrete tone. A decibel level which is near the hearing threshold is within approximately 5 decibels or less of the hearing threshold. These tones are passed into a bone vibrator from a speaker coupled to the discrete tone generator. Then the bone vibrator is gripped in the person""s teeth who is receiving the test. Accordingly, the discrete tones generated can be heard by the person to test their current hearing threshold.
An alternative embodiment uses a discrete tone sequence or a number of different frequencies which each have separate decibel levels. This embodiment may also use multiple frequencies at each discrete decibel level or multiple decibel levels for certain groups of frequencies. Additionally, the multiple tones or frequencies can be generated at the same decibel level which is just above a person""s hearing threshold.
The method for testing a person""s hearing threshold uses the steps outlined below. First, a bone vibrator is applied to one or more external bones in a person""s head. This bone vibrator is preferably gripped in the teeth. A processor with a memory generates a pre-programmed tone sequence with two or more discrete tones near a hearing threshold with a pre-specified decibel level for each tone. Then, the decibel level is automatically increased and the test is repeated until the person is able to hear at least one of the tones in the tone sequence. Finally, the person who received the test determines which discrete tones have been heard. The number of discrete tones which are not heard, as compared to the number normally heard, determines the threshold of the person""s temporary hearing loss.
These and other objects, features, advantages and alternative aspects of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description taken in combination with the accompanying drawings.